Monorepo skeleton, Prisma schema, core domain and services with tests

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

packages/core/src/index.ts

@@ -0,0 +1,14 @@
+export * from './types.ts';
+export * from './flows/index.ts';
+export * from './params.ts';
+export * from './pricing.ts';
+export * from './time.ts';
+export * from './slots.ts';
+export * from './assignment.ts';
+export * from './cancellation.ts';
+export * from './deeplink.ts';
+export * from './membership.ts';
+export * from './promo.ts';
+export * from './settings.ts';
+export * from './payments.ts';
+export * from './catalog.ts';